壳体制品注塑工艺参数CAE优化分析

应用Moldflow软件对壳体制品注射成型工艺参数进行了优化分析,模拟出制品成型过程中的最佳注塑压力、锁模力、模具温度、熔体温度、注射时间、保压压力和保压时间、冷却时间。采用该成型工艺参数结合合理的注塑模具能注塑出最佳的塑料制品,为成型过程的顺利进行提供指导依据,模拟结果具有一定的理论意义及实际指导价值。     

随形冷却对车灯壳注塑成型翘曲变形影响分析

冷却系统的设计在注塑模具中非常重要,它关系到制品的冷却效率和成型质量。传统冷却水道通常为简单直行管道,冷却效果不理想。激光3D打印技术的出现使注塑模具随形冷却结构的制造成为现实。以某车灯外壳为例,设计了随形结构的冷却系统。利用有限元分析软件ANSYS瞬态热分析对比了直行与随形冷却设计的冷却效率和模腔温度场分布结果,同时使用模流分析软件Moldflow对比分析了两种冷却方案中制品的翘曲变形。结果表明,随形冷却设计使模腔表面温度场分布更均匀,且能更快速调控模具温度,缩短了注塑成型周期;更重要的是可大大降低制品的翘曲变形。     

ABS扣板注射成型工艺参数优化分析

通过模拟真实注射条件,应用Moldflow软件对ABS扣板注射成型工艺参数进行了优化分析,得出影响注射成型顺利进行的主要因素,并模拟制定出扣板注射成型的最佳注塑压力、锁模力、模具温度、熔体温度、注塑时间、保压压力、保压时间和冷却时间。采用该注射成型工艺参数并结合合理的注塑模具能注塑出最佳的ABS制品,为注射成型的顺利进行提供指导依据。     

注塑成型中制品的缺陷原因及其对策

注塑成型是塑料成型中最重要的一种工艺,注塑制品应用于国民经济的各个领域。所谓热塑性树脂的注塑成型工艺,是指将树脂加热熔融,熔体借助压力注入模腔,经冷却固化而得到一定形状制品的成型方法。注塑过程中树脂需经过受热软化、熔融、注塑、保压、冷却定型等五个阶段的物理变化过程。树脂内部将会产生大分子定向、结晶以及残余应力等。由于注射成型过程中的成型条件（如注射压力、螺杆背压、注射速度、注射量、锁模力、料筒温度、模具温度）的选择不当或模具本身存在的问题,会使注塑制品出现许多不良现象和缺陷。归纳起来可分为五大类…     

冷／热循环模具注塑技术

在注塑生产过程中,模具温度是影响部件质量高低的一个重要因素.一般而言,设置较高的模温通常可获得较高的部件表面质量.热/冷循环模具注塑技术是在注塑循环过程中,利用热循环控制模具温度的一种方法.该技术要求模具表面的加热温度要在塑料的玻璃化转变温度(Tg之上,以利于注塑,然后快速冷却模温,使部件冷固,以便于顶出.     

液晶显示器前壳变模温注塑数值模拟与结果分析

介绍了变模温注塑的成型原理,分析了变模温注塑的成型特点,对液晶显示器前壳注塑模具进行计算机辅助工程建模,并分别针对常规注塑和变模温注塑过程进行了填充模拟和冷却翘曲模拟。结果表明,与常规注塑相比变模温注塑能降低模内应力、减小翘曲量、减少甚至消除制品表面熔接痕、提高熔接强度等,明显提高了制品的质量。     

基于Moldflow与Fluent模拟流体对注塑模温的热响应研究

以螺纹转接头注塑模为例,通过应用Moldflow与Fluent创建不同工况下的注塑模型,模拟动态模温模具的加热和冷却,分析流体类别及流速对模具温度变化的影响,获取动态模温注塑热响应曲线。结果显示:冷却流体流速对模温的影响有明显的区间差异性;模具型腔表面温度变化幅度比成型件内大,加热介质为热水时更显著;介质流速快的平均模温比流速慢的高,其中传热油特别明显;同一介质加热温度越高,加热及冷却时的模温变化幅度越大;加热介质对模温变化影响存在滞后性,其中传热油更明显。     

基于NX和Moldflow的轮胎罩注塑成型模拟及试验验证

利用NX1851软件,对轮胎罩模型进行物理分析,该制品为大型薄壁制品。在Moldflow2018模流分析软件中,选择3D网格类型,根据实际YUDO热流道系统,构建模拟热流道系统;采用随形冷却的方式,对制品进行冷却。针对模具表面温度、熔体温度、顶出温度、注塑总时间,采用正交试验法进行研究,通过极差分析法,在模具表面温度40℃、熔体温度180℃、顶出温度134℃、注塑总时间55 s的情况下,轮胎罩制品的翘曲变形总量最小,为2. 95 mm。成型后的制品表面光洁,无注塑缺陷,经专用检具检验,得出轮胎罩定位孔等位置度,偏差在允许范围内;整体轮廓与检具间隙在允许范围内;顶端没有发生翘曲。     

温度外场对注塑制品微观结构调控的数值模拟研究

利用数值模拟软件重点研究了由快变模温工艺提供的不同温度外场对注塑制品微观结构的影响规律。对结晶型聚丙烯注塑成型的模拟结果表明:提高模具型腔表面温度能有效减薄冷凝层,并降低注射压力;残余应力则随之呈现先降后升的趋势,其分布更均匀。结晶分析模块的结果表明:制品的结晶取向因子整体上随模具型腔表面温度的升高而下降;模具型腔表面温度的升高有利于增大制品晶体的平均粒径,但模具表面温度过高会导致制品晶体的平均粒径减小。     

蒸汽加热变模温注射成型数值模拟与结果分析

采用Moldflow软件对变模温注射成型过程进行数值模拟。利用蒸汽加热和冷却水冷却的变模温注塑工艺,研究不同蒸汽加热时间下注塑位置处压力以及制件冷凝层的变化规律,同时分析了制件表面和模具型腔表面的热响应规律。结果表明,相比于传统注射成型工艺过程,变模温注射成型通过提高注塑充填过程中模具温度,使得制件冷凝层出现在充填阶段之后;随着模具加热时间从10、15、25 s增加到40 s,注塑位置处最大注射压力从87.0608、84.6064、79.6863 MPa减小到74.4342 MPa,大大提高了熔体注塑充填过程中的充填能力;通过不同的蒸汽加热时间,制件表面和模具型腔表面可以获得不同的温度值,同时通过模拟获得了传热系数对制件表面温度的影响。     

注塑件变形分析

注塑件变形始于塑料的收缩,型腔中压力梯度、温度梯度以及剪切应力的客观存在导致了注塑件各部位收缩的不均一.本文分析了注塑成型过程中简单收缩、冷却、分子取向等因素对注塑件变形的影响.通过对实际零件的分析,阐述了模具设计中通过优化型腔设计、冷却系统设计、浇口设计来减小零件变形的具体方法.     

Numerical Simulation for Effects of Injection Mold Cooling on Warpage and Residual Stresses

Abstract

The dimensions quality of the injection‐molded parts is the result of a complex combination of material, part, and mold designs and process conditions. In this article, warpage prediction relies on the calculation of residual stresses developed during the molding process. The solidification of a molten thermoplastic between cooled parallel plates is used to model the mechanics of part warp in the injection‐molding process. Flow effects are neglected, and a thermorheologically simple thermoviscoelastic material model is assumed. The warp and residual stresses numerical simulation with finite element method (FEM) is time dependent. At each time step, the material properties can be temperature and pressure dependent. Mold temperature or mold‐cooling rate effects on part warp have been numerically predicted and compared with experimental results. By showing the mold‐cooling effects, it was concluded that mold cooling has a significant effect on part warpage, and mold‐cooling parameters, such as mold temperature, resin temperature, cooling channels, etc., should be set carefully.     

Investigation of the Effect of Molding Variables on Sink Marks of Plastic Injection Molded Parts Using Taguchi DOE Technique

The quality of an injection molded part is affected by material properties, mold geometry, process conditions etc. Obtaining optimum process conditions and mold design is the key problem to improve the part quality. Sink mark is one of several important flaws of injection molded parts. In this article, numerical simulation is combined with Taguchi design-of-experiment (DOE) technique to investigate the influence of process conditions and cavity geometry on sink mark of the injection molded part and optimize process conditions and cavity geometry. An L18(3⁷) orthogonal array based on the Taguchi method was conducted to minimize the sink marks of injection molded parts, and the significance of each factors on sink mark was investigated. For the factors selected in the main experiments, part thickness, holding pressure, melt temperature and mold temperature were found to be the principal factors affecting the sink marks of the injection molded parts.     

不均匀冷却对注塑件残余应力的影响

采用数值方法研究了不同冷却速度,不均匀模壁温度对塑件残余应力的影响。残余应力的计算采用二维积分型热粘弹本构方程,算例说明了数值算法的有效性。     

The influence of injection molding parameters and blowing agent addition on selected properties,surface state,and structure of HDPE parts

The investigation of the influence of injection molding parameters (injection velocity, mold temperature and injection temperature, and additionally, as a result of these three parameters change, injection time, hold time, and cooling time) and blowing agent percentage on selected properties of HDPE molded parts such as weight, density, mechanical properties (tensile strength and elongation at maximum force), surface state (gloss and color), and structure was the aim of this work. The examination showed, that the mold temperature has the main influence on properties and surface state of molded parts from solid and foam HDPE. The weight, density, mechanical properties and gloss of molded parts increased with the increase in mold temperature. The mold temperature also influences significantly the number and size of pores in molded parts. The addition of blowing agent in a quantity of 2% is sufficient to obtain parts with favorable mechanical properties and good surface quality. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers.     

A simplified method for analyzing mold filling dynamics Part I: Theory

A graphical method based on dimensional analysis is presented for estimating the injection pressure and clamp force required for injection molding amorphous polymers to form disk-shaped parts with a constant wall thickness. A procedure is suggested for estimating clamp force when the projected area of the mold cavity is smaller than the surface area of one side of the molded part. The results reported here are based on a numerical simulation of a power-law fluid filling a cold mold at a constant injection rate. The dimensionless bulk temperature and the ratios of the nonisothermal injection pressure (clamp force) to the isothermal injection pressure (clamp force) are given as functions of the dimensionless cooling time τ, the Brinkman number Br which characterizes viscous heating, the power-law exponent n, and a dimensionless temperature β which includes the inlet melt and mold wall temperatures and the temperature coefficient for viscosity.     

Optimization and numerical simulation analysis for molded thin‐walled parts fabricated using wood‐filled polypropylene composites via plastic injection molding

Plastic injection molding is discontinuous and a complicated process involving the interaction of several variables for control the quality of the molded parts. The goal of this research was to investigate the optimal parameter selection, the significant parameters, and the effect of the injection‐molding parameters during the post‐filling stage (packing pressure, packing time, mold temperature, and cooling time) with respect to in‐cavity residual stresses, volumetric shrinkage and warpage properties. The PP + 60 wt% wood material is not suitable for molded thin‐walled parts. In contrast, the PP + 50 wt% material was found to be the preferred type of lignocellulosic polymer composite for molded thin‐walled parts. The results showed the lower residual stresses approximately at 20.10 MPa and have minimum overpacking in the ranges of ?0.709% to ?0.174% with the volumetric shrinkage spread better over the part surface. The research found that the packing pressure and mold temperature are important parameters for the reduction of residual stresses and volumetric shrinkage, while for the reduction of warpage, the important processing parameters are the packing pressure, packing time, and cooling time for molded thin‐walled parts that are fabricated using lignocellulosic polymer composites. POLYM. ENG. SCI., 55:1082–1095, 2015. © 2014 Society of Plastics Engineers     

Integrated simulation to predict warpage of injection molded parts

Injection molding analysis programs were developed for CAE (Computer Aided Engineering) in injection molding of thermoplastics. The programs consist of mold cooling, polymer filling-packing-cooling, fiber orientation, material properties and stress analyses. These programs are integrated to predict warpage of molded parts by using a common geometric model of three dimensional thinwalled molded parts. The warpage is predicted from temperature difference between upper and lower surfaces, temperature distribution, flow induced shear stress, shrinkage, and anisotropic mechanical properties caused by fiber orientation in the integrated simulation. The integrated simulation was applied to predicting warpage of a 4-ribbed square plate of glass fiber reinforced polypropylene for examination of its validity. Predicted saddle-like warpage was in good agreement with experimental one.     

Predicting mechanical properties of acrylonitrile-butadiene-styrene terpolymer in injection molded plaque and box

A methodology to predict mechanical properties in injection molded parts has been developed. Knowledge of part properties before actual molding and testing will be of immense help to part and mold designers in modification of design. This methodology involved the application of connectionist learning systems, injection molding computer simulation, and experimental evaluation of mechanical properties, to relate the thermomechanical history of injection molded parts to the resulting part properties of injection molded parts are dependent upon their thermomechanical history which in turn is greatly influenced by the processing conditions and part geometry. As the relationships between engineering properties and thermomechanical history are complex and highly nonlinear, the methodology developed was based on a backpropagation neural network algorithm that provided the means for a nonparametric mapping between the part properties and thermomechanical history. The proposed methodology has been successfully applied to two geometries, plaque and box. This methodology provides designers with the ability to predict mechanical properties in injection molded parts when significant thermomechanical history can be obtained from injection molding simulation.     

基于正交实验法的电视机支柱成型工艺优化研究

以电视机透明支柱实体塑料件为例,在三维模流分析理论研究的基础上确定塑料件质量评价指标为体积收缩率。影响质量的工艺参数为模具温度、熔体温度、注射时间、保压压力、保压时间和冷却时间。结合正交实验法、CAE分析及数据处理技术,确定各工艺参数对塑料件质量的影响及最优工艺方案。